LAS VEGAS -- New Mexico expected a tough matchup from Boise State in the Mountain West Conference tournament semifinals, and the Lobos got it.

Cameron Bairstow's 10-foot baseline jumper with 42.2 seconds left pushed No. 20 New Mexico's lead to seven, while his two free throws with 3.8 seconds left sealed the 70-67 victory over the Broncos on Friday night.

Bairstow finished with 23 points and eight rebounds to lead the Lobos (26-6), who advance to Saturday's championship game against San Diego State, a team they split with during the regular season.

"(I) knew it was going to be a tough matchup for us," New Mexico coach Craig Neal said. "It always has been when we play them. It's just a tough matchup for us because they play small and we play big. Really happy for our guys. They hung tough, fought hard."

Bairstow connected on 15 of 18 free throws. His made free throws set a conference tournament semifinal record, and put him third all-time in Mountain West tournament history.

Derrick Marks led the Broncos (21-13) with 20 points. Thomas Bropleh added 16 points before being ejected at the 7:15 mark of the second half, after being called for a flagrant-two for clotheslining Bairstow under the basket.

"The kid made a play on the ball," Neal said. "He's playing hard, competing at a high level. I just think he got caught with the rule. The rule is that anything around the head, it's a flagrant two. I think he made a good play on the ball and ended up getting Cam's head. There's no way he did that on purpose. I think it was just an accident. He's just trying to compete at a high level. ... It's a misfortunate accident or foul that took place."

Boise State coach Leon Rice said: "There's never any doubt in my mind that he would ever try to intentionally hurt a guy. But the rule is the rule."

The ejection motivated the Lobos as they scored the next four points to extend their lead to six after Delaney picked a misfire off the rim and slammed it home, and Bairstow hit a field goal a minute later.

But the Broncos wouldn't go away. After falling behind by 10 points early in the first half, the Broncos clawed their way back in the second half to tie the game at 46-all with 10:25 left.

Boise State had a chance to tie it with 3.8 seconds remaining, but New Mexico's stringent defense forced Nick Duncan to go over-and-back at the center line and turn the ball over back to the Lobos.

With the loss, the Broncos' NCAA tournament hopes are likely dashed, and they're now hoping for an invitation to the NIT.

"It's just tough to make it (to the NCAA tournament) every year," Rice said. "As you can tell, New Mexico and San Diego State and those teams, they've got a system down, they've figured out how to get there. Unfortunately we couldn't get there this year."

New Mexico, which never trailed Friday night, has now won eight-consecutive conference tournament games, tying the record with San Diego State, which won eight straight spanning the 2010-12 tournaments. The Lobos are aiming to become the first team to win three consecutive Mountain West tournament titles, but will be playing on seemingly tired legs after their late game with Boise State.

"I had to play them a little bit longer than I wanted to play them," Neal said. "Hopefully they'll be able to get back and get some rest and get ready for tomorrow."

The Lobos are 8-0 all-time when seeded second in the tournament. And in all-time Mountain West championship meetings, No. 2 seeds are 5-0 versus No. 1 seeds.